In the explosives art as it is known today, particularly in its application to military uses, a stringent requirement is placed on the igniter of an ignition charge. The ignition of a charge of an explosive device by means of blasting caps, electrical igniters, and detonators in general, is expected to be achieved with a maximum precision in a manner to effect the ignition of the charge at its geometric center. As is known, when a charge is ignited at a point other than its geometric center, the ignition front progresses from the ignition point in an oblique direction with respect to the geometrical center of the charge and ignition penetration of the charge is thereby considerably lessened.
In order to achieve an optimum performance, it has been attempted to position the igniter over the geometric center of the charge. This did not alleviate the problem since a conventional igniter is not guaranteed to effect ignition at a specific point. The primary pellets of the blasting caps are not always symmetric but hang a distance from the axis of the blasting caps or on the wall of the blasting cap shell. The shower of sparks emanating from the primary pellet moves in the inner cap at an oblique direction and impinges on the initiating charge not at the geometric center but at an edge thereof. As a result of this asymmetrical ignition, ignition front is generated which progresses obliquely to the axis of the charges and propagates itself in asymmetric fashion.